The present invention relates to products particularly those for use in contact with the human body.
Sunscreens are any type of topical product that can absorb or reflect Ultraviolet A (UVA) or Ultraviolet B (UVB) radiation from sunlight, and therefore help protect the skin against sunburn and other potential harmful effect of the sun. Excessive UV radiation exposure is the leading cause of primarily non-malignant skin tumours.
The first sunscreen was reported to have been invented by Franz Greiter in 1938; the product ‘Glacier Cream’ became the basis for Piz Buin company, who took their name from the area in Switzerland that inspired Greiter's cream. Greiter in 1962 also developed the concept of a Sun Protection Factor, which has become the worldwide standard for measuring the efficacy of sunscreens when applied at an even rate of 2 milligrams per square centimetre (mg/cm2).
The Ultraviolet radiation has different properties dependant on its wavelength. The UV spectra can be split into 3 types, as discussed below:
1. UVA radiation penetrates the skin more deeply than UVB or UVC (which is blocked by the Ozone layer) reaching the dermis through the epidermis. The effect of UVA exposure on the skin includes pigment darkening, photo aging and indirect DNA damage which can lead to the formation of cancerous cells.
Protection from UVA radiation is measured using 2 standard tests—Persistent Pigment Darkening and an In-Vitro UVA test. In Japan products receive either a PA+, PA++ or PA+++ rating depending on their efficacy. In Europe, the COLIPA UVA symbol can be applied to products whose UVA Protection Factor is at least ⅓ of the SPF value.
2. UVB mostly penetrates the skin only as far as the epidermis and exposure only occurs outdoors. The effect of UVB radiation includes sunburn, delayed tan, skin thickening and direct DNA damage. UVB protection is investigated using the Sun Protection Factor test. The SPF is derived from the smallest dose causing an erythema (reddening of the skin) with sunscreen compared to without sunscreen.3. UVC, which doesn't reach the earth, as it is blocked by the ozone layer.
There are two types of sunscreen agents, UV reflectors (Physical Sunscreens) and UV absorbers (Chemical Sunscreens).
1. UV reflectors or physical sunscreens protect the skin from the sun by deflecting or blocking the sun's rays. Titanium Dioxide and Zinc Oxide are the most commonly used physical sunscreens, as they are inorganic particles they cannot be absorbed by the body. Therefore they can form a filter on the skin which reflects or scatters UV radiation. Zinc Oxide is the only true UV reflector as Titanium Dioxide has both reflector and absorber properties. Zinc oxide is particularly good at reflecting UVA radiation. UV reflectors by nature tend to be thicker than UV reflectors and are often harder to apply. They also tend to leave the skin white or tinted. In addition, as they are a physical medium they tend to rub off more easily and therefore have to be reapplied more frequently.2. UV absorbers or Chemical Sunscreens absorb the UVA and UVB radiation and convert them into harmless heat. An important feature is that the absorber molecules convert the energy without reacting with other molecules or being destroyed. These filters respond to the UV radiation by undergoing a short-term internal rearrangement reaction known as a H shift. The absorbed UV radiation stimulates the molecule and one hydrogen atom migrates to a different position inside the molecule. When converted back into its original state, the energy absorbed as UV light is gradually released as heat, allowing the molecule to absorb further radiation. This mechanism ensures effective and long-lasting protection. They tend to be colourless, odourless and runny which makes them the ideal ingredients for sunscreen creams or lotions.
Physical sunscreens (UV reflectors) tend to be better tolerated by most skin types and are particularly goo for sensitive skin. However, they tend to leave a white cast or white streaks after application and don't offer as much UVA protection compared to chemical sunscreens. Physical sunscreens present in lotions are also a bit thicker so they are often more difficult to apply. Physical sunscreens are difficult to formulate with, thus require thicker and heavier bases or emulsions to ensure stability. Since reflectors and absorbers have their advantages and disadvantages, many of today's sunscreens contain both UV filters. However, knowing whether a sunscreen is physical, chemical, or both does not give enough information about whether a particular sunscreen will be a protective one. The most effective sunscreens provide protect across the entire UVA/UVB spectrum.
The general public have a perfunctory attitude to cosmetic lotions that provide protection from UVA and UVB radiation from sunlight. Consumers only apply sunscreen lotions when the weather conditions obviously demand it and the lotions within this field offer limited functionality when it comes to the considering the various requirements from the general public. This can often lead to the consumer either using the incorrect product, in the incorrect manner or potentially not protecting themselves at all from the harmful effects of the sun.
The present invention seeks to provide a sunscreen that addresses the problems of the prior art.